Character alignment and proportional spacing system



Se t. 27, 1966 M. HAUERBACH 3,276,008

CHARACTER ALIGNMENT AND PROPORTIONAL SPACING SYSTEM 2 Sheets-Sheet 2 Filed Aug. 8, 1963 MAR/WARD HAMEQBACH A7TOPNEY United States Patent 3,276,008 CHARACTER ALIGNMENT AND PROPORTIONAL SPACING SYSTEM Markvard Hauerbach, Mountain View, Calif., assignor to A. B. Dick Company, Chicago, 111., a corporation of Illinois Filed Aug. 8, 1963, Ser. No. 300,738 9 Claims. (Cl. 340324) This invention relates generally to a system for generating and displaying or printing characters and more particularly to means in such a system for aligning and for proportionately spacing such characters.

In co-pending US. patent application, Serial No. 305,- 879, entitled Character Alignment and Proportional Spacing System, filed on August 30, 196-3, by William E. Evans and assigned to the same assignee as the present application, means are disclosed for use in a system for generating and displaying or printing characters, for aligning and proportionately spacing such characters. Essentially, the invention in that .application is directed toward the provision of character position information along with character identity information on the target of a character generating means such as a monoscope tube or flying spot scanner. The character position information is in the form of a different guide 'bar area disposed beneath each character, each guide bar being of a length proportion-a1 to the space the associated character should occupy along a horizontal line of displayed characters. All guide bars are spaced from their associated characters by the same distance, this distance being utilized to align all displayed characters. Alignment is accomplished by controlling the scanning raster of a display cathode ray tube so as to initiate display tube scanning as soon as the beam of the character generating tube emerges from the guide bar area. This technique avoids misalignment due to indexing errors in the character generating tu be, such misalignment oc curring in prior art systems in which scanning rasters of both the character generating and displaying tubes were synchronously related.

In the cited co-pending application, the output signal derived from the character generating tube is applied to the control electrode of the display tube. In order to prevent thatportion of the character generating tube output signals representative of the beam emerging from the guide "bar area from being displayed, means are provided for separating that portion of the output signal from the other portions of the output signal comprising the video signal representing the character. Inasmuch as the beam emerges from the guide bar area in the initial portion (on the order of 10 percent) of each character generating tube scanning line, separation is accomplished by applying the character generating tube output signal together with a gating signal representative of the initial portion of each scanning line to an And gate. The output of the And gate constitutes a synchronizing signal which is used to initiate the display tube scanning raster. Inasmuch as the display tube scanning raster is not initiated until after the character generating tube beam emerges from the guide bar area the portion of the character generating output signal representative of this occurrence is not reflected in the display.

It is an object of the present invention to provide means in a character generating apparatus for initially developing separate video and synchronizing signals in a manner avoiding the necessity of separating these components out of a character generating apparatus output signal.

Briefly, the invention herein is directed to improved means for use in a character genera-ting and displaying system for aligning and proportionately spacing displayed characters. More particularly in accordance with the present invention, electrical signals representing charactors are generated by use of a flying spot scanner operating in conjunction with a two color target. Stored on the target in complementary colors are both character identity information and character position information. The respective pieces of information are respectively separately read through the utilization of light color sensitive apparatus which couples the character generating apparatus to character display apparatus.

In a preferred embodiment of the invention the target is partially transparent and includes a plurality of character regions, each region including character identity information in the form of a first area whose shape corresponds to the shape of a character to be displayed and character position information in the form of a second area comprising a guide bar. The first and second areas are transparent and formed of complementary colors, such 'as blue and yellow. The remaining area in each character region is opaque.

The guide bar in each region is horizontally positioned beneath the character in that region. The flying spot scanner develops a light spot which can be selectively deflected to any region on the target. Thence, the vertical scanning raster is generated which causes the light spot to trace vertical scanning lines. The raster is so positioned with respect to the character region and the scanning lines are sufficiently long so as to enable each scanning line to extend into the guide bar area and fully traverse the character area. The target is positioned between the flying spot scanner and a light color sensitive apparatus comprising a dichroic mirror. The diehroic mirror has the property of transmitting light of a first color and reflecting light of a complementary color. First and second light sensitive devices are positioned with respect to the mirror so as to respectively detect light reflected from and transmitted through the dichroic mirror. The first and second light sensitive devices are respectively connected through video amplifiers to means for triggering the display tube raster and means for controlling the display tube control electrode.

Although the illustrated embodiment of the invention constitutes a character generating and displaying system, it is pointed out that the teachings of the invention are equally applicable to systems other than display systems. For example, the synchronizing and video signals derived from the character generating apparatus could be equally as well used to control electrostatic printing apparatus or such. Consequently, the use of the term display system herein should be understood as including display, printing, and similar systems.

The novel features that are considered characteristic of this invention are set forth with particularity in the appended claims. The invention itself both as to its organization and method of operation, as well as additional objects and advantages thereof, will best be understood from the following description when read in connection with the accompanying drawings, in which:

FIGURE 1 is a block schematic diagram of a character generating and displaying system in accordance with the present invention; and

FIGURE 2 is an illustration of a character generating transparency target in accordance with the present invention.

Attention is now called to FIGURE 1 of the drawings which illustrates a character generating and displaying system. The character generating apparatus includes a cathode ray tube 10, which has means for generating an electron beam therein. The tube 10 also includes a phosphorescent face which has the known characteristic of providing a spot of light where contacted by the beam. The light spot can be moved to selective positions on the 3% face of the tube by deflecting the beam under the influence of voltages applied to horizontal deflecting plates 12 and vertical deflecting plates 14.

The beam in the tube 10 can be selectively positioned in response to digital information provided by a data pulse source 16. The output of the data pulse source 16 is connected to the input of indexing circuits 18 which function to convert the digital signals provided by source 16 to analog deflection voltages. The indexing circuit 18 is provided with horizontal and vertical output terminals 20 and 22, which are respectively connected to the inputs of adder circuits 24 and 26.

A small raster generator 28 is also provided. The small raster generator 28 includes horizontal and vertical output terminals 30 and 32, which are also connected to the inputs of adder circuits 2.4 and 26'.

The indexing circuit 18 provides direct current voltage levels to the adder circuits 24 and 26 in response to the digital positioning information provided by the data pulse source 16. On the other hand, the small raster generator 28 provides a saw-tooth voltage output waveform on each of its output terminals. It is assumed herein that a vertical scanning raster consisting of a series of vertical scanning lines, each line being horizontally displaced by an incremental distance, is desired. Consequently, in a well known fashion, the small raster generator 28 provides a high frequency sawtooth waveform on its vertical output terminal 32, and a low frequency sawtooth waveform on its horizontal output terminal 30. The outputs of the adder circuits 24 and 26 are respectively coupled to the horizontal deflection plates 12 and the vertical deflection plates 14. The requisite operating voltages for the tube 10 are derived from the high voltage circuits 34.

The apparatus thus far described constitutes a flying spot scanner. In operation, a light spot on the face of the tube 10 can be deflected in response to digital signals provided by the data pulse source 16 to a selected region on the face of the tube 10. Thereafter, under the control of the small raster generator 28, the spot can be caused to trace a series of vertical scanning lines, each scanning line being horizontally displaced an incremental distance from the preceding scanning line.

The scanning light spot provided by the tube 16 is utilized to enable information to be read from a transparency target 36, and coupled to a cathode ray tube 38, for display purposes.

An objective lens 40, is positioned between the face of the cathode ray tube 18 and the target 36 to focus the light spot provided by the tube 10 on the target. A condensing lens 42 is positioned on the side of the target 36 remote from the tube 10. The condensing lens 42 is utilized to focus light transmitted through the target 36 onto a dichroic mirror 44. Positioned to receive reflected light from the dichroic mirror 44 is a first light sensitive element 46. A second light sensitive element 48 is positioned behind the dichroic mirror 44 to receive light transmitted through the mirror 44.

Prior to proceeding with a description of the apparatus coupling light sensitive elements 46 and 48 to the display tube 38, attention is called to FIGURE 2 which illustrates in detail the transparency target 36.

The target 36 is divided into a plurality of character regions, for purposes of illustration, the regions being arranged in a 4 X 4 rectangular matrix. Disposed in each character region is character identity information in the form of a first area 50 whose shape corresponds to the shape of a character desired to be displayed. Positioned beneath the character area in each character region is a second area in the form of a guide bar 52. The upper surface of the guide bar 52 is spaced a precise distance from the lowermost portion of the character area 50 in each of the character regions. This distance is the same for all of the character regions.

The length of each guide bar 52 is utilized to define the amount of horizontal space that the character associated therewith should occupy in a displayed line of characters. More particularly, in conventional high quality printing, different characters in the same font have different widths. The space along a line devoted to each character is preferably proportional to the width of the character. Note for example that the character i occupies a smaller horizontal space than the character I. The character r in turn occupies a smaller space than the character R. The length of the guide bar 52, as will be more readily appreicated below, controls the apparatus associated with display tube 38 to cause the associated characters to be displayed in spaces proportional to the character width.

The guide bars 52 are defined by transparent yellow areas and the characters are defined by transparent blue areas. The remaining area on the tar-get 36 is opaque.

In order to (generate a character, the light spot generated by the tube 10 is caused to scan a character region in the manner represented by the scanning lines superimposed -over character s in FIGURE 2. Note that the initial scanning lines are positioned to the left and extend below the guide bar 52. Subsequent scanning lines intersect the guide bar 52 and yet do not intersect the character 50. Subsequent scanning lines intersect both the character 50 and guide bar 52 and still subsequent scanning lines intersect the guide bar 52 without intersecting the character 50.

The dichroic mirror 44 has the property enabling it to transmit light of a blue color to light sensitive element 48 and reflect light of a complementary color (i.e., yellow), to light sensitive element 46. Consequently the light spot scanning a character region on the target 36 will initially scan only an opaque area which of course will not permit any light to fall on light sensitive elements 46 and 48. Subsequently, during several scanning lines light will be incident only on light sensitive element 46' since the scanning line will intersect the guide bar 52 without intersecting the character 50. Subsequently, for several scanning lines light will be incident upon both light sensitive elements 46 and 48 and still subsequently light will be incident only on light sensitive element 46. Note however that for each scanning line that light is incident on light sensitive element 48, it will also be incident on light sensitive element 46.

The output of light sensitive element 46 is coupled through a video amplifier 54 to horizontal and vertical scanning generators 56 and 58. The output of horizontal scanning generator 56 is connected to the input of adder circuit 60 and the output of vertical scanning generator 58 is connected to the input of adder circuit 62. A display format generator 64 is provided which has horizontal and vertical output terminals 66 and 68. The display format generator 64 provides direct current voltage levels on the terminals 66 and 68 which function to deflect the beam in tube 38 to a selected position on the face thereof. Output signals derived from the horizontal and vertical scanning generators 56 and 58 cause the beam in tube 38 to trace a vertical scanning raster similar to that traced by the beam in tube 10, on the face of tube 38. Control over the beam in tube 38 is of course effected by connecting the outputs of adders 60 and 62 to the horizontal and vertical deflection plates 70 and 72, respectively.

The output of the vertical scanning generator 58 comprises a high frequency sawtooth voltage and the output of the horizontal scanning generator 56 comprises a low frequency sawtooth voltage. Each sawtooth cycle from the vertical scanning generator is initiated by a signal provided by the video amplifier 54. Each incremental linear increase in the voltage provided by the horizontal scanning generator 56 is similarly initiated by a pulse provided by the video amplifier 54.

The light sensitive element 48 is coupled through a video amplifier 74 to the control electrode of the display tube 38. The requisite operating voltages for the tube 38 are derived from the high voltage circuits 76.

In the operation of the preferred embodiment illustrated, the beam in tube is selectively deflected by indexing circuit 18 in response to digital signals provided by data pulse source 16 to move the light spot generated on the face of the tube to a position causing it to be focused in the opaque area to the left of and below the guide bar 52 in the selected character region of the target 36. Under the influence of the small raster generator 28, the spot is moved to generate the vertical raster illustrated superimposed over the character s in FIGURE 2. As soon as the light spot intersects the guide bar 52, light will be reflected from the dichroic mirror 44 and be incident upon the light sensitive element 46. Light sensitive element 46 Will consequently generate a pulse which will be coupled through video amplifier 54 to horizontally displace the beam in tube 38 an incremental distance and to cause it to trace a vertical scanning line. A subsequent scanning line traced by the light spot scanning the selected character region on the target 36 will cause another scanning line to be traced by the beam in tube 38. So long as the light spot does not traverse the character area 50 on the target 36, no light will be incident upon light sensitive element 48 and no pulses will be coupled through video amplifier 74 to the control electrode of tube 38. Consequently, tube 38 will not generate a display at this time, although the position of its beam will be moved. When the light spot does intersect the character area 50, blue light will be incident on light sensitive element 48 and information will be coupled through the video amplifier 74 to trace the character information on the face of tube 38. After a complete character region has been traversed by the light spot, no further pulses will be developed by element 46 and the beam in tube 38 will wait until the next character is processed.

From the foregoing, it should be appreciated that a horizontal space, in a line of characters displayed on the face of tube 38, proportional to the length of each guide bar 52 will be occupied by the character associated with the guide bar. Moreover, it should be apparent that as a result of the vertical scanning generator 58 being triggered on by the light spot intersecting the guide bar 52 in each character region, and since the space between each character and its associated guide bar is the same in all character regions on the target 36, all displayed characters will be in vertical alignment.

As previously noted, although the embodiment disclosed comprises a character generating and displaying system, the invention is equally as applicable to other systems, as for example electrostatic printing systems in which an electrostatic cathode ray printing tube is utilized in lieu of display tube 38. In addition, although the light derived by the dichroic mirror 44 has been illus trated as being transmitted through the target 36, it should be apparent that the teachings herein are applicable to systems in which the light incident on dichroic mirror 44 is reflected from target 36. Moreover, light color sensitive apparatus in the form of conventional filters can be utilized in lieu of dichroic mirror 44.

What is claimed is:

1. A character display system including a flying spot scanner capable of producing a light spot; a target having first and second areas thereon respectively formed of first and second complementary colors; said first area having the shape of a character to be displayed and said second area comprising a bar spaced from said first area and having a dimension proportional to the space in which said character is to be displayed; means positioning said flying spot scanner relative to said target for causing said light spot to be incident upon said target and for generating a light signal of a first color when said light spot is incident upon said first target area and for generating a light signal of a second color when said light spot is incident upon second target area; means responsive to said light signals of said first and second colors for respectively developing first and second electrical signals; a display cathode ray tube having a display face; means for generating an electron beam in said display cathode ray tube; means for deflecting said display cathode ray tube electron beam to a selected position on said display face; generator means for causing said display cathode ray tube electron beam to scan said selected position; means responsive to said first electrical signal for controlling said display cathode ray tube electron beam; and means responsive to said second electrical signal for actuating said generator means.

2. The display system of claim 1 including a plurality of first target areas; a plurality of second target areas each associated with a different one of said first target areas, all of said second target areas being spaced by an identical distance from the first target area associated therewith.

3. The display system of claim 1 including means responsive to said dimension of said bar for displaying said character in a space proportional to said dimension of said bar.

4. A character display system including a target having a plurality of regions thereon, each of said regions including a first transparent character identity information area having the shape of a character to be displayed and a second transparent character position information area; said first and second areas respectively being of complementary colors; a flying spot scanner including means for producing a light spot and moving said light spot to generate a raster; means for deflecting said light spot to cause it to be incident on one of said regions; dichroic means; means positioning said flying spot scanner with respect to said target and said dichroic means relative to one another for enabling said light spot to be transmitted through said transparent areas of said one of said regions and be incident on said dichroic means; first and second light sensitive means respectively responsive to light transmitted through and reflected from said dichroic means for developing electrical signals representing said character identity and character position information; a display cathode ray tube having a display face; means for generating an electron'beam in said display cathode ray tube; means for deflecting said display cathode ray tube electron beam to a selected position on said display face; generator means for causing said display cathode ray tube electron beam to scan said selected position; means responsive to said electrical sig nal representing said character position information for actuating said generator means; and means for controlling said display cathode ray tube electron beam in response to said electrical signal representing said character identity information.

5. A character display system including a target having a plurality of regions thereon, each of said regions including a first transparent character identity information area having the shape of a character to be displayed and a second transparent character position information area; said first and second areas respectively being of complementary colors; cathode ray tube light spot generating means including first vertical and horizontal scanning raster generators for moving said light spot to gen erate a raster; means for deflecting said light spot to cause it to be incident on one of said regions; dichroic means; means positioning said flying spot scanner with respect to said target and said dichroic means for enabling said light spot to be transmitted through said transparent areas of said one of said regions and be incident on said dichroic means; first light sensitive means associated with said dichroic means for developing a timing pulse in response to said light spot being transmitted through said second transparent area; second light sensitive means associated with said dichroic means for developing a video signal in response to said light spot being transmitted through said first transparent area; a display cathode ray tube having a display face; means for generating an electron beam in said display cathode ray tube; means for defiectingsaid display cathode ray tube electron beam to a selected position on said display face; a second vertical scanning raster generator; a second horizontal scanning raster generator; means coupling said second vertical and horizontal scanning raster generators to said display cathode ray tube for causing said display cathode ray tube electron beam to traverse said selected position in response to each of said timing puses; and means for controlling said display cathode ray tube electron beam in response to said video signal.

6. The display system of claim 5 wherein each of said second transparent areas has the shape of a bar spaced from the first area associated therewith.

7. The display system of claim 6 wherein the spacing between the first and second areas isthe same in each of said plurality of regions.

8. The display system of claim 6 wherein each of said bars has a dimension proportional to the space in which it is desired that the character associated therewith be displayed; and means responsive to said dimension of the bar in said one of said regions for displaying the char- References Cited by the Examiner UNITED STATES PATENTS 2,834,005 5/ 1958 Ketchledge. 2,834,831 5/1958 Gifford 340--324.1 X 3,196,393 7/1965 Siegrnund 340 146.3

FOREIGN PATENTS 1,192,975 10/1959 France.

OTHER REFERENCES A Generalized Scanner for Patternand Character Recognition Studies, Proceedings of the Western Joint Computer Conference, 1959, pages 291-94.

NEIL C. READ, Primary Examiner.

A. J. KASPRE, Assistant Examiner. 

4. A CHARACTER DISPLAY SYSTEM INCLUDING A TARGET HAVING A PLURALITY OF REGIONS THEREON, EACH OF SAID REGIONS INCLUDING A FIRST TRANSPARENT CHARACTER IDENTITY INFORMATION AREA HAVING THE SHAPE OF A CHARACTER TO BE DISPLAYED AND A SECOND TRANSPARENT CHARACTER POSITION INFORMATION AREA; SAID FIRST AND SECOND AREAS RESPECTIVELY BEING OF COMPLEMENTARY COLORS; A FLYING SPOT SCANNER INCLUDING MEANS FOR PRODUCING A LIGHT SPOT AND MOVING SAID LIGHT SPOT TO GENERATE A RASTER; MEANS FOR DEFLECTING SAID LIGHT SPOT TO CAUSE TO TO BE INCIDENT ON ONE OF SAID REGIONS; DICHROIC MEANS; MEANS POSITIONING SAID FLYING SPOT SCANNER WITH RESPECT TO SAID TARGET AND SAID DICHROIC MEANS RELATIVE TO ONE ANOTHER FOR ENABLING SAID LIGHT SPOT TO BE TRANSMITTED THROUGH SAID TRANSPARENT AREAS OF SAID ONE OF SAID REGIONS AND BE INCIDENT ON SAID DICHROIC MEANS; FIRST AND SECOND LIGHT SENSITIVE MEANS RESPECTIVELY RESPONSIVE TO LIGHT TRANSMITTED THROUGH AND REFLECTED FROM SAID DICHROIC MEANS FOR DEVELOPING ELECTRICAL SIGNALS REPRESENTING SAID CHARACTER IDENTITY AND CHARACTER POSITION INFORMATION; A DISPLAY CATHODE RAY TUBE HAVING A DISPLAY FACE; MEANS FOR GENERATING AN ELECTRON BEAM IN SAID DISPLAY CATHODER RAY TUBE; MEANS FOR DEFLECTING SAID DISPLAY CATHODE RAY TUBE ELECTRON BEAM TO A SELECTED POSITION ON SAID DISPLAY FACE; GENERATOR MEANS FOR CAUSING SAID DISPLAY CATHODE RAY TUBE ELECTRON BEAM TO SCAN SAID SELECTED POSITION; MEANS RESPONSIVE TO SAID ELECTRICAL SIGNAL REPRESENTING SAID CHARACTER POSITION INFORMATION FOR ACTUATING SAID GENERATOR MEANS; AND MEANS FOR CONTROLLING SAID DISPLAY CATHODE RAY TUBE ELECTRON BEAM IN RESPONSE TO SAID ELECTRICAL SIGNAL REPRESENTING SAID CHARACTER IDENTITY INFORMATION. 